1. Field of the Invention
The present invention relates in general to electronic systems and in particular to a system for flexibly interfacing the various components of an electronic system.
2. Description of the Art
Many electronic systems employ field programmable gate arrays (FPGAs), such as those manufactured by Xilinx Inc., to reconfigure selectively system component interconnections for various modes of system operation. A typical FPGA includes several input and output ports and a network of logic gates interconnecting the input and output ports wherein the logic gates respond to signals at the input ports by generating signals at the output ports. The FPGA also includes a number of memory cells that store data transmitted thereto from an external source such as a computer. The memory cells control switching states of various gates in the FPGA. by appropriately loading data into the memory cells, the computer can configure the FPGA in order to generate an output signal at any given port that is a selected logical combination of states of input signals at one or more of the input ports. Thus the FPGA may be used for selectively routing signals between system components and may also be used to perform various logic operations on the signals.
While programmable FPGAs are very useful, they have some limitations. All input/output signals must be unidirectional, and all signals must be of the same logic level. Thus the FPGAs cannot be connected to bi-directional buses and cannot interface differing types of devices such as CMOS and TTL devices.